I think it depends what style you're aiming for. If you're trying to slick back for example I think it would be more symmetrical. Barber might be assuming you're combing sideways and cutting for that. Maybe you need to talk about what style you're aiming for and see if they get it right.

I grew out my hair on top and i wear it to the right side. My barber always leaves the hair on the left side (the side of my part) longer and i've found it weighs down the rest of my top and makes it hard to style and get volume/texture. Basically the hair starts from the part and goes fully across the top of my head and it sort of lays flat.

So to fix this would i just ask him to trim that side so it's even with the rest of my hair? I get a haircut tomorrow so some help would be appreciated.

Should the length of hair on top be even?